Projection viewing and calculating device



c. H. si'oKwELL PROJECTION VIEWING AND CALCULATING DEVICE Filed oct. 22, 1949 May 12, 1953 5 Sheets-Sheet l IN V EN TOR.

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PROJECTION VIEWING AND 4CALCULATING DEVICE Filed Gct. 22, 1949 5 SheetS-Shet 2 5 Sheets-Sheet 3 OOOQTOQmm l Qoom cOom QQmQ OOC# 0Com- 00mm @Oom OCOr- Com@ l boom 0Com- OSE` OCS.

'- c. H.v STOCKWELL PROJEtiToN VIEWING AND cAL'cULAT-ING 'DEYICE Filed Oct. 22, 1949-...

May 12, 1953 c. H. s'rocKwELL fPRoJ-ECIION VIEWING AND CALCULATING DEVICE Filed oct. 22, 1949.

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PROJECTION VIEWING AND CALCLATING DEVICE Flg. '7

BEE/M Patented May 12, 1953 lU.ISIfIllf-'l-D PATENT FICE l PRouEo'rIoNlvIEWING v`AND CALCULATING 'DEVICE Clifford-Estockwell, Ottawa, Ontario, Canada 'ipplcation"Ootober'lZZ, 1949,1S'eria`l'No. 122,919

(CUSS-L24) r'invention' relatesto a; meansfor vobtain- .ingireadings fromfgrapha'fchartsrand? the'ilike.

Ihe' invention :Willibe described .with particular :reference -to a'means "for obtaining ground Fele- 'rations from :parallax `.readings on raerial photographs.

In .the vusual lparallax barmethodfo'f `olutaininar suehfelevations, t'is common practice `to .u'se :parallaxA tables :which :involve acertain amount :of "interpolation :and afnumber o'f calculations. The' calculations, though :.sirnple, :are time fconsunxing,'especiallyl When-hundreds or thousands Aof -determinationsfare :to be :made and, moreover, `ealtperienee.-sl1o\1vsf thatltheyiare a `frequent.y source .-otierror.- 'It-'is usualto stai-taseriesrof'parallax readings at'. a -zcontrolcpoint fof `known elevation and to 'end ythe:series'fattanother `pointv of fkn'own f-eleva'tion. .LCorrections for tilt 'ofthe photograph, iaszi'rezvealed 4lily 'the' closing lferx'or, .maysubsefquently be made.

"It :is :a general'l objectrof'this .invention to proa fvide a simpliiied` means 'foriconvenientlyrand fquickly obtaining. ."desired:` readings :and ;'ca'lcula ftionsifrom a zplurality Joi variable 'if actors.

...it viisa unth'er 1 obj ect i of I this invention :to pro- .vide a simplified and more convenientlmeans for ohtainingcgroundfelevationafromiparallaxmead- :ings'onraeri-al .photographsgwhere'in asubstantial ysavingpf' itimefis effected-Land the possibility'fof Lerror:considerablyfz'reduced.

.Anotherfobjectiistofproridera simple and-effecftive `rTvriewing meansfort'he graph.

objects, details andvadvantagesl of fthe invention will become apparent'asfthe description -:proceeds Withparticular :referencelto' the?. accom- F culating or viewing instrument for use with the ".Eigurei 8 :is afsectionalfp-lan` 1ffiewoftheviewing Vi=instrument and j Figurefl'is a diagrammatic viewof an vin'rage 'of'fthegraph :as producedibythe instrument.

Irl-accordance withfthel invention,l a graphconsisting of two partsil and 2'is provided-,ea'ch:part being in elongated strip form as shown. Part'lis provided withparallaxreadingsifor various focal and `-'base'lengths, 'while part "2 is `providedfftlith Velevations for 'various'flying' heights. *Knowing 'the flying height, focal flengfth .and baseflength vthe graph "is set yby' sliding fone part'f-relatively to `theother until a` control v'pointe' ofiknownfelevationis opposite VtheI corresponding lparllax reading. Then, with lthis setting, "the elevtiun ofany other point (uncorrected lfor tilt)' isfreaid directly opposite Iits-parallaxreading.

, The parallaxeequation-used'in the'co'nstruction :ofboth Iparts of -the Ygraph is 'f thefabsoluteiparallax. )if-the ffocal'length: of Lthe': cantera;y in? millhnetres.

5B Lthe photo fbasexthatr-.isn the ldistancelbetween photo centers, in feet. H :the height of the aeroplane, feet, above sea level. hzthe height of the ground, in feet, above sea "level,

:Part 1 may :be called the -.p fB.-.graph, :.Wh'ere p is .the parallax reading; -V par-t2` maybe. called the-h-,fHfgraph Y j ji'Ihei-pfa graph,4 or part-.1,isconstructed with lp'f asordinates and the ,produca fB,-as abscissae. The f-B values: are .indicated as Ya-plurality of :parallel rlines I extending. longitudinally -otthe Astrip and 'which are 4equally spacedatascale of, YSa-y, .3inch, for a-i-.difference of 5000 .and remain f equally. spacedv throughouttthe length-fof the diagram. Instead of continuing the-clivisionlinesrl `assolid linesfextending throughout the length of itheV :strip they fmay #comprise @a series of `short lines, as` shownin Figure '2, .which are repeated fat intervals throughout the 4rlength Aof Vthe vgraph Y:part 1. `fAt such intervals, a rangez-offfB yvalues "are indicated on Vthe-lines I As shown by Way of example in Figure 2, the elinescl"indicate'the f product fB'plotted lot-itvveenthe ran'ge'-,fB=700.,000 'to f 25800g000. 'The ranges for eaoh-intervallare indicated vin :Figure l, the f'entire? rangeiin the graphfillustrated being I3:00000 tol-4,000,000. Ehe parallax values areplotted: onlthe .graphy foreach .interval range `of iB Values,\.as .indicated in Figure 1. These are shown as gently 'sloping-JinesS ings.

ltoy 3,000,000-4,000,000.

.a which may be slightly curved and which are spaced at intervals of .1 parallax. The scale for these is constant for a iixed fB value but varies inversely with changing values of fB. Thus, when the scale chosen for the parallax readings is .50 to l inch for JB:1,000,000, the scale for other values of jB is obtained from the formula where S is the scale for fB:1,000,000 and S is the scale for any other value, fB. In the skeletn form shown in Figure 1, only parallax lines 0, 10, and 30 are shown, but Figure 2 shows the intermediate lines to provide readings at intervals of .1 parallax.

The diagram on the graph gives directly all JB values from 400,000 to 4,000,000. This amply covers the commonly encountered range. However,

should any other value be required the same vgraph can be used by simply applying a factor of 10. For example, for an yB value of 300,000 the .graph for 3,000,000 can be used; or, for an JB .value of 5,000,000, the graph for 500,000 can be used.

It will be observed that the graph generally gives a range of from 0 to 30 in the parallax read- This range has been chosen because it is theone generally covered by parallax bars. For low Values of ,fB a range 0-20, and 0-10 only is plotted merely to save space, as this range will generally be suicient for such low values. For parallax differences greater than 30, the greater `'va-lues aremerely added on the parallax bar and, correspondingly, are added on the graph by inaking the necessary shift in its position.

A manner of constructing part 1 of the graph, when 10 p:1 inch and fB:1,000,000, will now be described. On a vertical line representing fB:1,000,000, mark off points 0, 10, 20, and on lthe scale of 10:1 inch. Draw vertical line fB:900,000 at a distance of .3 inch to the left of vertical line fB:1,000,000 (i. e., the horizontal fB scale is 1,000,000900,000:100.000 to .3 inch). When fB:900,000 the parallax (vertical) scale is 10p to lOn the vertical line representing fB:900,000,

mark off points 0, l0, 20, 30 on the scale of 10 to f1.1`1 inch, the starting point, 0, having been chosen in a position such that, when points 0, 10, 20 and 30 on the 900,000 line are joined with the Acorresponding points on the 1,000,000 line, the

slopes of the lines 0 and 30 are about equal, a1-

though in opposite directions. For convenience Aand in order to conserve space on the graph, line 15 is, arbitrarily, made approximately horizontal,

and therefore lines with values less than 15 slope downwardly and those with values greater than 15 slope upwardly.

A similar procedure is employed for plotting the range fB:800,000 to ,fB:900,000 and so on down to the range 400,000 to 500,000, excepting that parallax lines 0 to 20 only are plotted in the Arange 500,000 to 600,000 and excepting that parallax lines 0 and 10 only are plotted in the frange 100,000 to 500,000.

Also, a similar procedure is employed for plotting p values in the ranges 1,000,000-1,200,000 up In these sections of the graph, however, the JB scale, instead of being 100,000 to .3 inch, is as follows:

vRanges l,000,0()0-1,200,000-1,400,000: Scale 200,000 t0 .3 inch 4 Ranges h1,400,ooo1,700,000-2,000,000; saaie 300,000 to Ranglelel;2,000,000-3,000,o00-4,000,000: Scale 1,000,000 to .3 inch These changes in the fB scale are for the purpose of keeping the slopes of lines 0 and 30 at about the same angle in all cases.

Part 2, or the h, H graph, is constructed with h as ordinates and H as abscissae, and a satisfactory manner of constructing such graph will now be described. The H values are indicated by vertical lines constituted by the longitudinal edges of the strip 2 and a plurality of intermediate lines 2 parallel Ito such edges. The H values are plotted at a scale of, say, 1.2 inches for a difference of feet, which scale remains constant throughout the length of the graph. It is unnecessary to `draw lines 2 in full throughout the length of the strip, it being preferable to indicate the divisions by a series of short lines (such as illustrated in Figure 4) repeated at intervals along the length of the graph.- The .letters H, H, H represent various ranges of H values, as indicated in Figure 5, and are applied to sections of the graph, as shown in Figure 3. These ranges are employed for the purpose of very greatly reducing the width of the graph. Thus, when using the graph, H is mentally taken to be any H value in the even thousands from 3000 to 29,000, whichever is required, as shown in the table of Figure 5. Correspondingly H" is taken to be an H Value 500 greater (for instance, when H:3000, H" is 3500, etc.). Likewise, when H" is 3500, H is 4000, and so forth. It will be apparent that, without this use of H', H and H", the graph would have to be many times wider than it is, and would be so cumbersome as to seriously affect its use from a practical point of view.

In Figure 4, the values of H shown are in the range from H to vH. For example, if the height of the aircraft, H, is 29,160 feet, then H':29,000 and H:29,500 and the line marked is 29,160.

In Figure 3, values 0I" H from H' to H are shown in the two columns that makeup the left half of the gure, and values of H from H to H" are shown in the two columnsV that .make up the right half.

The h values appear as generally sloping lines 4, which may be slightly curved and which vare indicative of and marked for each difference of 10 feet, as clearly shown in Figure 4. .For convenience, lines 4 representing 1000 feet divisions are indicated by the letters A, B, C, etc., the marking for the lines in each division `being from 10 to 990, as shown.

The position of the h lines is determined from the formula With fB being given a value of 1,000,000, the absolute parallax is found for each diierenoe of 10 feet in h for the full length of the graph. Taking H:30,000 feet as an example:

Published reciprocal tables may be used in obtalning the values of p. The values of p are plotted on the same scale as that used in the p",

fB graph when fB:1,000,000, that is in thefexample being used, .50 parallax to 1 inch, :except inzthenluweivmtrrofffthe graph. 'wherezethe mung increasmmzy rnpidly,;they arefplotted mftthisfscale.- Thai-Plots may'fhefrmade..fon-a.

the grzphzand nidicatedtasathe line H".=;inzFlgure '3,5zand #che sh ,points markedxoiffzaand` numbered.

'Bhe :plottingzris started icm H fatthe where it is met by cross'zlineaefandsends;fat'-'the pointrwheme itlis metg-by. .cross lineL-Zff". .iF-Ihescale used fromdine Aft'o lineyiisthesame as zwasrused.

for the p' yvalues in the p', 'jB-.crgraph whenA fB=1,000,000, that is, .1 parallax to .2 inch. Frm`line YY to aline 2"' :when fthe distance xlietween `cross jf lines :fincrezaesedv` .'very 'rapilmfithe scale used is 'T16 of the first scale.

Similarly, vor aan' H lvfalue-of, -say,;29,990,wand agameusirig thefsame formula .,i,0.0.0,0.0.0. .l When h-Q, H A/h 99,999, andpm 294990 M3334:

the .h values fare, determined land marked :on theline H:'29j9.9'0,and so on for theao'ther Values o'fH.

[It 'maybe observed that,l 'for other. values of H,.it.'is urmecessaryito repeat the :calculations since'it. vvv'ill he. Observed that,'for example., the parllaxyalue for h1-:0 when H;`2999.0 isy the, same as .'for `h=310 when'. H :30,0001feet, or, as ,andther-'illustration,'the parallax value, )for hO when' y1..-' '2$I,10(l0 .is the. same ;as2.fo1'. iff-:1100.0 when H.; `;.'.3Q`,0100. `The samelongstrippo'f paper can thusbe..used.yin plottingxall'lthe. points., which are then .joinediby .smooth curves. "To v,ereaclly' shorten: the .lengtl .of the graph .arid thus render' the same'nct too. cumbersome "for ,practical use;

aesystem of indication..o'i '.the .cross .'lnes .lllby letters sie; .B,".-C, etc., for, the. various isectionsf thepgraph are...emi5loyed, 'as' indicated inlFigpre`3 incoriiundtion. with .the table shd\vn':in`-Figure5 Thusgin thegarrangemen't Shown. injFigulelB,

.The .table 5. endg/ralph. part. 2V areearranged to.

yleferring,to, -Figure.3,f it will be.; yliseivgedthfnt; the,:graph ;is1.broken atcurvesztWfand Y,;:as..indi. cated;.:at f6.' v'This -is .desirablef-in` .order .te prevent, thecslopes of. .the curvesfrom .becoming1s`msteep.. that .they couldA not be read -coveniently'or ,ac-f. cnrately. .To crossone :of the resulting gaps; involyesxa re-settingof lthe `Iii-.h1gl'ftph withfrenspect: toV the; p', .JB gr ap,h. .Howeven S.1'1.ch...slight, incQrivemiericel will rarely 'be encountered f. since,v mostv Qperations will fallin the, rangefahove-curyef Wx. It iislalso desirable to plot curves Y to: ZffwoJs-i; lfthefscale ,of .the other curves. Thisfi-s 'because the ,great :increasefiri scale this.l range, would'y otherwise gis/,e :unnecessarily accurate resulte; For this. sectionpfgthe graphl the ipafalaxsief ing; gobtained '.on lthe parallax bar is thelieorediyideby 10, before -theggl'qrphis rused,

;practice, the =va-rio11s applications ofvv the factor j 10 willfrarely;besiiecessary, evenawheri-- applied, willuscarcely be .-a source`` of errore t.- :be .rat once. apparent; if .the:elevaticms-t are ten times too large` or .ten;,tiI..11S; t0n small.v

1r-will be apparent. that.; each graph parti-fin orderztozcover fthe desired range -of' variablesand on asuiiciently -largezscale tozprovide `aaccur-,ate results, :would .be .too large and unwieldy toelage cenvenientlyfused; in itsgoriginalyform. Thug in, accordance withV the` inventien,` `each, part of? `the original :graph ,isf .reproduced -in :microscopiciscale onrgaeroll, strip or band off-film, for `subsequent.- projection of; portiensthereof as. .an .enlargedimage-.omascreea suitable viewer.; or viewing., instrument, fior the projection -ofzsuch ,imaee$, will now be described.

Referripgftoliigures, 6;.to&9:inclusive,.thercalcuorfviewipg'. ,instlillment :therein illustrated comprises a suitablecasirig r1 in- A.vrlliicli'are mounted: two: pairs :of y.take-up :speels-8, and l 9 One ,pair :of spcolsfisfadapted ato. receive-:and support -afroll-of` film lil, .on ,Whichis reproduced. graph-partl-l, Themother ,pairwo-.spools .are adaptedto. :receive andsupport, aroll of film l I', on :which,isfreproduced graph. part. .2. .Each ,film

maybe standard,.-Derforated 35mm,y The spools are.mriounted-inv fixed relation Aori .respective .shafts L2 .and `I t., the .ends of which. .are journalled inV theesidewallsfof thecasng andin Aari .iriterniediatepartitionmember I4. It v,Willihe'observed that,.as. shown, .each pair of .'spoolsgis in :vertically paced relation, 'theI lower spoel heilig, Posi--, tioned'somevvhatiorwardly of the. upper met and the upper. and;lower spoolsbeing-in'laterally aligned, relation.

Eachifllfllm" in. its. travel from. .ODC SglULOQl4 t0, the' ether passes over an upper idler roller ,I8 andfa lower sprocket. roller 23 `or 20', thesprockets'of Whichfit 'into .the perforations in `the'lm, The rearward surfaces of 'the rollers' [9 vandzll or 20" are vertically aligned to .provide a `.Vert-i'cally travelling-portion of eachl lm.

Means are provided for ranually rotzal'firifg sprocket rollers 2k3, 2t either independentlyjof each other or in .unison to kcause corresponding the other'end of 'roller' 20', and lockI nuts 25 tol adjust the frictional contact pressure between.

the Afriction disc and roller as appliedby the spring 24.

to a shaft 2'I, journalled in the side wall of the casing and in member I4, a gear 28 fixed to shaft 21, and a gear 29 meshing with gear 23 and fixed to a respective roller 20, 20. It will be apparent that, with roller 2li frictionally coupled to shaft 22', rotation of either knob will act to rotate both rollers 20, 2d in unison, but that, by grasping one knob 26 to restrain it from rotative movement,

the other knob 2G'v (with its respective lroller-2liy or 20') may be rotated against the action of friction disc 23 to provide independent rotation Resilient means connecting each pair of shafts i2 and I3 are provided to hold the lm taut between the respective spools of each pair and to allow for increasing and decreasing diameters as the film is wound or unwound from one spool to the other. Such means comprises a non` slip belt or chain I engaging a wheel or sprocket` I 6 journalled on shaft I2 and a wheel or sprocket I1 fixed to shaft I3, sprocket It being connectedv to shaft I2 by'means of a spiral spring I8 having one end fixed to shaft I2 and the other end fixed f to sprocket I6.

It will beobserved that only one of. each pair of spools has a resilient connection as described." Thus, tension'on the spring i8 holds the film'taut' against the equal and opposite pull on the connecting chain I5. As the spool is rotated, the spring I8 revolves as a whole therewith. The rate of revolution of one spool with respect to the other varies slightly due to the increase or decrease in diameters as theiilm is wound or un- Wound. The change in diameters (and corresponding relative rates of revolution) are taken up by a gradual and slight increase or decrease inthe tension of the spring I8. Thus, the iilm is held taut in all positions and there is no tendency for it torun back when the hand knob 26 is released. Considerable lengths of lm may be employed in the arrangement illustrated. For instance, nine feet of film can be rolled from one spool to the other with a tightening. of the spiral spring of by only about one-half a turn. The tension of spring I8 may be set as desired before the film or belt is attached and this tension then' remains substantially constant throughout the range of operation.

Means for holding the rollers and films in any position tol which they are moved by knobs 26 may comprise a leaf spring 39, through which shaft 22 extends, and a pair of lock nuts 3i mounted on the shaft and in frictional engagement with the spring. It will be apparent that the lock nuts may be adjusted to vary the frictional pressure as desired.

`Means for projecting images from the lms includes a pair of laterally aligned lamps 32, mounted in a rearward compartment 33 of the casing.v The beam of light S4 from the filament 35 of veach lamp passes through a heat-absorbing glass sheet 36, a pair of condenser lenses 3l, thence through the respective section of nlm I0 Separate means for applying direct rotative movement to each roller 2li, 2Q comprisesv a handwheel 26, having a turning knob 26', fixedA Li, U

. constituted by a pair of sheets of Polaroid glass or: Il,"and apair of projection lenses38.'l The pair of beams are reilected downwardly by an' inclined iirst surface mirror 39 and then upward- 1y by an inclined first surface mirror 40, the

mirrors being suitably vmounted in the casing 'i as shown. Finally, the pair of images, in juxtaposed relation, as indicated at`42 and 43, are thrown on a screen 4I. It will be observed that the screen 4I is mounted in a recessed Well 4I' in the upper portion of the casing, for adequate shading from extraneous light and for convenient viewing by the operator.

For satisfactory operation of the viewer described, the lfollowing details are given by way of example only: A 1

Focal length of projection lenses-2 inches. y Useful diameter of projection lenses-.8 inch.

Magnication--6-7X- v l Size of light laments-.4 inch x 1.2 inch.

Focal length of condenser lenses- .86 inch.

The condenser isshcwn as a cylindrical lens to illuminate the full width of about .94 inch of the graphs but only .45 inch of their length.

' Only a part .of the full width of each graph is seen on the screen at one setting. Lateral movement of the projected image for the purpose of bringing it to any desired position is accomplished by lateral movement of the projection lenses 33.

ing knob 45 liked to each worm screw outside the casing for convenient rotation and consequent lateral adjustment of the frame and lens, The lenses and lens mounts are held ina verticali position by plates 47 along which the mounts vent the projected images from overlapping, ay

pair of Polaroid glasses 48, 48 are preferably placed in the paths of the respective light beams and are oriented at right angles to one another.

It is also proposed that the viewer screen 4I be 49, 49', frostedon the upper side. Sheet 49v is oriented parallel with glass 43 and sheet 49' parallel with glass 48.

.A The junction of the two Polaroid sheets 49, 49

makes a sharp fore and aft line 50, dividing thel screen in half. A short cross hair 5I is pref-4x erably marked across the screen as shown.

A viewing instrument, such as describedabove,A may be constructed of convenient size. Such size need not exceed, for instance, one foot long by' eight inches high by six inches wide.

In operation, knob 45 connected to the lens 38v through which the image of graph lpart 1 on film II) is projected isturned until the desired JB number coincides with line 50 on the screen. Knob 45 connectedto the other lens 38 through which the image of graph part 2 on lm II is projected is then turned until the desired H number coincides with the same line 50. These two This is eifected by means con-v,` nected to each lens 33 comprising a worm screw- 44 journalled in the casing and from which the lens mount 46 is suspended, and a manual turn? ner (film H being held stationary in its set position) until the corresponding parallax reading falls at the cross hair 5|. With this setting, either knob 26 may he turned to cause both films to travel unison, whereby, for any parallax reading faliing at the cross hair 5i, the corre spending elevation may also be read at the cross hair. Desired corrections of the elevations for tilt may later be made if desired.

It will be recognized that a number of varations may be made in the arrangement of the graph and in the design of the viewing instrument.

What is claimed is:

1. A viewing instrument for at least two indicia-bearing bands of iilrn comprising a casing, a pair of supporting spools for each nlm band, a. screen, means for simultaneously projecting an image from a portion of each film band in laterally aligned relation on said screen, said means including a projection lens for each llrn band, means mounting said lenses in the casing for lateral adjustment with respect to each other to adjust laterally7 the portion of said images on the screen, said screen comprising a pair of laterally aligned and angularly oriented Polaroid glass sheets, said sheets having meeting edges along the longitudinal center line of the screen., and manually operable means for causing travelling movement of said each iilm band selectively in unison with and independently of each other to project images of desired portions of the graphs on the screen.

2. A viewing instrument for at least two in dicia-bearing bands of lm comprising a casing,

10 having a recessed well in the upper portion thereof, a pair of supporting spools for each film band, a screen mounted at the base of said well for shading from extraneous light, means for simultaneously projecting an image from a portion of each nlm band in laterally aligned relation on said screen, said means including a projection lens for each film band, means mounting said lenses in the casing for lateral adjustment with respect to each other to adjust laterally the portion of said images on the screen, and reectors for directing the projected images onto said screen, said screen comprising a pair of laterally aligned and angularly oriented sheets, said sheets having meeting edges along the longitudinal center' line of the screen, and manually operable means for causing travelling movement of each film band selectively in unison With and independently of each other to project images of desired portions of the graphs on the screen.

CLIFFORD H. STOCKWELL.

References Cited in the le 0f this patent UNITED STATES PATENTS Number Name Date 520,114 Johnson May 22, 1894 753,840 Barth et al Mar. 8, 1904 1,794,147 Chidester Feb. 24, 1931 1,894,684 Hawk Jan. 17, 1933 1,918,468 Harding July 18, 1933 1,962,805 Chenicek et al June 12, 1934 2,008,982 Hopkins July 23, 1935 2,301,274 Greiser Nov. l0, 1942 2,375,878 Willens May 15, 1945 2,511,270 Kahan June 13, 1.950 

